Generally, various types of electric/electronic equipment or devices are connected to power supply sources through electric connectors (e.g., outlets and plugs), and are supplied with power required for operation. However, of these electric connectors, the outlets are open at their first ends such that plugs can be inserted thereinto from the outside, and thus various types of impurities may easily infiltrate thereinto from the outside in the state in which the plugs have been inserted thereinto.
In particular, an outlet or plug used in places having a large amount of water or moisture, such as a bathroom, an outlet or plug used for devices using electricity outdoor, such as a vending machine, an aquarium, a game machine, a refrigerator, etc., or an outdoor outlet or plug temporarily installed in a construction site or outdoor place has a problem in that rain water or moisture infiltrates from the outside to the inside and thus concern about the occurrence of a safety-related accident, such as a short circuit and electric shock, is high.
Furthermore, most conventional plugs and outlets use a coupling method in which each plug is simply inserted into each outlet. Accordingly, when the outlet and the plug are connected to each other, there frequently occurs a case where contact terminals located inside the outlet are not tightly connected to the terminal pins of the plug. In this case, the plug may be easily separated from the outlet by a small amount of external pressure, with the result that there frequently occurs a problem in which current is cut off and thus electric/electronic equipment or an electric/electronic device is stopped during operation.
In order to overcome the above problems of the conventional electric connectors, numbers of waterproof outlets and plugs, such as those shown in the accompanying FIGS. 1 and 2, have been introduced recently. However, these conventional waterproof outlets and plugs are configured such that the outlets are connected to the plugs in the state in which the plugs are simply surrounded with waterproof caps. These conventional waterproof outlets and plugs are structural defects in which rain water (including water) or moisture cannot be prevented from infiltrate into a cap between one side end of each plug body and a wire and also in that the waterproofing of a portion where each plug and each outlet are connected, as well as the waterproofing of the outlet itself, is impossible.
Prior art documents regarding the above-described waterproof electric connectors are as follows: Document 1: Korean Patent Application Publication No. 10-2008-0046465 (Waterproof Plug; filed on Nov. 22, 2006); and Document 2: Korean Patent No. 10-1219019 (Waterproof Plug and Outlet Structure; filed on May 23, 2011).